In the related art, it is always required for performance of a power converter to be high efficiency, high power density and high reliability. Being high efficiency means having low energy consumption, which is helpful for energy conservation and emission reduction, environmental protection, and reducing of the usage cost. Being high power density then means small volume, light weight, which is capable of reducing cost for materials and transportation, and reducing the requirement on space. Being high reliability means longer service life and lower maintenance cost.
Semiconductors are one of the important factors determining the efficiency of the power converter. In the power converter, some assistant devices, such as fixtures, screws for fixing the semiconductor devices, thermal pads for assisting heat dissipation and so on, are inevitably required. Since there are a large amount of the discrete semiconductor devices constructing the power converter, resulting in cumbersome in mounting these assistant devices. Moreover, for the purpose of standardization, generally, the space utilization ratio (ratio of the volume of the chips to the volume of the package) for these discrete semiconductor devices is extremely low. For example, for the typical TO-247 package, the space utilization ratio is generally below 40%.
In order to meet the requirement for further improving the performance of the power supplies, an integrated power module is gradually developed. The integrated power module is to integrate a plurality of power chips as well as other devices on one piece of substrate, thus achieving higher space utilization ratio. Meantime, in order to further improve the heat dissipation ability and reliability of the power module, currently, molding compound having high thermal conductivity is used to seal all the devices into a block body, and the heat may be dissipated by conducting the same to a heat sink of the integrated power module via the molding compound; at the same time, the molding compound may improve the mechanical strength of the overall integrated power module, and protect the power chips therein against the invasion of the outside humid and corrosive gas, thus the reliability of the integrated power module even the system may be improved.
FIG. 1 shows a structure of the typical integrated module in the prior art, the integrated module is a power module, and includes a power chip 11, a magnetic component 12 such as a transformer, an inductor, or the like, a controlling chip 13 and a passive component 14 such as a resistor, a capacitor, or the like, all of the components are welded on a PCB (printed circuit board) 17, and electrical connections are formed between the components. The integrated module is further connected to an external system board through pins 15. The pins 15 may include a plurality of pins having different functions, such as power pins, signal pins, and so on. In order to dissipate the heat from the integrated power module more effectively, a heat sink 1 may be further mounted on a top surface or a bottom surface of the integrated power module.
The integrated module as described above has higher integration level and power density, however in a power supply system, generally, a plurality of integrated modules are needed, and the plurality of integrated module will occupy large footprint on the system board. In order to further reduce the footprint of the plurality of integrated modules, two or more integrated modules may be stacked on each other, to form a stack structure.
With reference to FIG. 2, FIG. 2 shows a conventional stack structure, the stack structure includes two stacked integrated modules 10, and these two integrated modules 10 are adhered together by an adhesive layer 18 therebetween. The corresponding pins of the two integrated modules 10 are fixedly connected by welding or adhering.
The above conventional stack structure may effectively reduce the footprint, however it still suffers from one or more problems as follows: 1) the two integrated modules are stacked after each of the integrated modules is made separately, resulting a complex production procedure, low efficiency and high production cost; 2) the corresponding pins between the two integrated modules are connected by welding or crimping, resulting the process to be more difficult; and 3) the connection positions between the pins of the two integrated modules have low connection strength, thus the reliability for the electrical connection and the mechanical connection is poor, and failure of the power supply system is easily occurred.
The above information disclosed in the background technology section is only used to facilitate understanding the background of the present disclosure, and thus it may include information which does not construct the prior art well-known by the person skilled in the related art.